Psoriasis is a chronic skin disease that is characterized by scaling and inflammation of the skin. The scaling occurs when the cells in the outer layer of the skin reproduce faster than normal and pile up on the skin's surface. Psoriasis affects about 1.5% to 2% of the North American population. It occurs in all age groups and affects men and women equally. People affected by psoriasis suffer from discomfort, restricted joint motion and emotional distress. About 10% of people suffering from psoriasis have joint inflammation that produces symptoms similar to arthritis.
When psoriasis develops, patches of skin thicken, redden and become covered with silvery scales. These patches are generally referred to as plaques. The plaques are usually itchy and can burn. Psoriasis most often occurs on the elbows, knees, scalp, lower back, face, palms and soles of the feet.
A variety of treatments and methods have been used over the years including the topical application of corticosteroids, calcipotriene, coal tar, etc. Bath solutions and general moisturizers have been utilized by some patients. Sunlight and ultraviolet light treatments have also been used. In some instances systemic treatment using prescribed medicines taken internally are needed. Drugs taken internally include retinoids, methotrexate, hydroxyurea and antibiotics.
Each of these treatments has its benefits and drawbacks. In many instances, patients develop a tolerance to the treatment and the treatment becomes much less effective. The inventors have sought a treatment suitable for a variety of patients that overcomes the drawbacks noted above.
Mahonia aquifolium was originally found in the Pacific Northwest and British Columbia where it has been used for the treatment of psoriasis and eczema by Native North Americans for many centuries. It is an evergreen shrub that belongs to the Berberidaceae family.
The root and bark of the Mahonia aquifolium plant are known to contain isoquinoline alkaloids that include berberine, palmatine, berbamine, oxyacanthine, jatrorrhizine, bervulcine, magnoflorine and columbamine. These alkaloids are thought to be the active constituents of the plants as many of them have shown strong in vitro anti-microbial and anti-fungal activity. Mahonia aquifolium may have several mechanisms of action in the treatment and management of psoriasis and other inflammatory conditions. Berberine and related alkaloids as noted above reversibly intercalate in DNA hindering replication and transcription. Mahonia extract contains isoquinoline alkaloids as outlined above. Isoquinoline has been identified as a component of coal tar which causes interfollicular regions of parakeratotic stratum corneum in mouse tail epidermis to become orthokeratotic, with concomitant production of a granular layer. In this respect, isoquinoline behaves similarly to coal tar and the isoquinolines may contribute to the anti-psoriatic activity of coal tar. Alkaloids isolated from the extract demonstrate anti-proliferation activity on keratinocytes. Hyper proliferation of keratinocytes is a major symptom of psoriasis and so controlling this activity will assist in the treatment of psoriasis. Lipoxygenase inhibition is strongly correlated with the lipid antioxidant effect of the protoberberine alkaloids, perhaps by reducing lipid hydroperoxide substrate accumulation. Mahonia is a moderate inhibitor of LTB-4 (a leukotriene which is believed to mediate inflammation) and 5-hydroxy-eicosatetraenoic acid (5-HETE) with an IC-50 in the same order of magnitude as anthralin. IC-50 refers to the concentration at which 50% inhibition occurs.
Mahonia aquifolium extract is also a very potent inhibitor of lipid peroxidation. Individual alkaloids isolated from the extract demonstrate anti-inflammatory activity by inhibiting the action of lipoxygenase. Oxidation products resulting from the action of lipoxygenase are known to be mediators of inflammation in other biological systems. The inhibitory effect of Mahonia aquifolium on lipid peroxidation contrasts with anthralin, which slightly stimulates lipid peroxidation. This difference may explain why Mahonia aquifolium extract reduces irritation.